Secondary battery having a non-aqueous electrolyte

Abstract

A non-aqueous electrolyte secondary battery which comprises a positive electrode containing a lithium-containing oxide; a negative electrode containing a material capable of absorbing and releasing lithium; and a non-aqueous electrolyte containing a non-aqueous solvent containing at least one non-cyclic ester and which is excellent in storage stability at high temperatures is provided by adding an oxidation resistance improving agent such as triphenylmethane, tetraphehylmethane or the like.

What is claimed is:  
     
       1. A non-aqueous electrolyte secondary battery comprising: 
       a positive-electrode, the positive electrode comprising a lithium-containing oxide;  
       a negative electrode comprising a carbonaceous material and  
       a non-aqueous electrolyte comprising a non-aqueous solvent, the non-aqueous solvent comprising at least one non-cyclic ester and an oxidation resistance improving agent, said oxidation resistance improving agent being an aryl-substituted alkyl compound in which 3 or more alkyl groups are substituted with aryl groups.  
     
     
       2. A non-aqueous electrolyte secondary battery according to  claim 1 , wherein the oxidation resistance improving agent is represented by the formula (1):                    
       (where Ar is an aryl group and R1 is a group selected from the group consisting of hydrogen atom, aryl group and lower alkyl group). 
     
     
       3. A non-aqueous electrolyte secondary battery according to  claim 1 , wherein the oxidation resistance improving agent is selected from the group consisting of substituted or unsubstituted triphenylmethane, triphenylethane, triphenylpropane, triphenylbutane, triphenylpentane, tetraphenylmethane, tetraphenylethane, tetraphenylpropane, tetraphenylbutane, tetraphenylpentane, pentaphenylethane, pentaphenylpropane, pen taphenylbutane and pentaphenylpentane. 
     
     
       4. A non-aqueous electrolyte secondary battery according to  claim 2 , wherein the oxidation resistance improving agent is triphenylmethane or tetraphenylmethane. 
     
     
       5. A non-aqueous electrolyte secondary battery according to  claim 1 , wherein the total amount of the oxidation resistance improving agent in the non-aqueous electrolyte is in the range of 0.1-20% by weight based on the total weight of the electrolyte. 
     
     
       6. A non-aqueous electrolyte secondary battery according to any one of claims  1 - 5 , wherein the non-cyclic ester is at least one compound selected from the group consisting of dimethyl carbonate, diethyl carbonate and ethylmethyl carbonate.